A side-viewing endoscope in which a treatment tool can be guided into pancreatic and bile ducts using a guidewire is conventionally known in the art. The endoscopes in Patent Literature Nos. 1 and 2 are one example of such an endoscope, and are provided with a raising-base accommodation recess formed in an outer peripheral surface of a distal-end proximity of an insertion portion that extends from a control body, a treatment-tool insertion conduit formed inside the insertion portion so that the distal-end opening and the raising-base accommodation recess are communicably connected with each other, and a raising base, provided in the raising-base accommodation recess, which is rotatable about a rotational shaft that extends in a widthwise direction of the insertion portion. The raising base rotates in accordance with an operation of a controller provided on the control body, and is rotatable about the above-mentioned rotational shaft between a non-raised position, at which the entire raising base is positioned within the raising-base accommodation recess, and a raised position, at which part of the raising base outwardly projects from the raising-base accommodation recess. Furthermore, in Patent Literature No. 1, a wire-engaging groove, having a V-shaped cross section, is formed on the surface of the raising base and is positioned at the distal-end opening side of the treatment-tool insertion conduit when the raising base is positioned at the raised position, and the recessing amount of the V-shaped wire-engaging groove is increasingly greater in a widthwise direction from either side of the raising base toward a central portion of the raising base. Furthermore, in Patent Literature No. 2, a guidewire engaging groove, having an approximate V-shape in a side-elevational view, is formed through a side of the raising base as a through-groove (which extends through a side wall of the raising base).
When an operator carries out a treatment on a pancreatic or bile duct with a treatment tool using the above-described endoscope, first the distal end of the insertion portion of the endoscope is inserted into the duodenum via the patient's mouth, esophagus and stomach, and the aforementioned raising-base accommodation recess is positioned at the close vicinity of the duodenal papilla (to face the raising-base accommodation recess against the duodenal papilla). Thereafter, a flexible catheter is inserted into the opening, at the control-body side, of the treatment-tool insertion conduit of the endoscope, and the distal end of the catheter protrudes from inside the raising-base accommodation recess via the opening at the distal-end side of the treatment-tool insertion conduit. Furthermore, the distal-end proximity of the catheter is brought in contact with the raising base while the distal end of the catheter is made to project toward an outer peripheral side of the insertion portion. Thereafter, the distal end of the catheter is oriented toward the duodenal papilla by rotating the raising base toward the raised position while operating the controller, and the distal end of the catheter is inserted into the duodenal papilla by pushing (moving) the catheter toward the distal end thereof. Subsequently, a contrast agent is injected so that the bile duct or the pancreatic duct can be observed by radioscopy.
Subsequently, the flexible guidewire is inserted inside the catheter from the opening thereof on the control-body side, the distal end of the guidewire is projected from the opening of the catheter at the distal end thereof, and the distal end of the guidewire is inserted into the duodenal papilla. Thereafter, the distal end of the guidewire is inserted until a desired location in the bile duct or the pancreatic duct while the bile duct or the pancreatic duct is observed by radioscopy. Upon indwelling the guidewire thereat, the catheter is pulled out from the treatment-tool insertion conduit (and the patient's lumen) of the endoscope along the guidewire. In this pulling-out operation, first the distal end of the catheter is drawn into the treatment-tool insertion conduit (toward the control body relative to the raising-base accommodation recess) while the base end portion of the guidewire is manually grasped.
Subsequently, in Patent Literature No. 1, the operator rotates the raising base toward the raised position by operating the controller while engaging an intermediate portion of the guidewire into the wire-engaging groove of the raising base. Thereafter, since the intermediate portion of the guidewire is forcibly bent by the wire-engaging groove, the vicinity of the intermediate portion is pushed against at a location opposing the wire-engaging groove of the raising base. Therefore, if a large frictional force between an inner peripheral surface of the catheter and the outer peripheral surface of the guidewire is incurred upon the operator pulling the catheter (which is inserted in the treatment-tool insertion conduit) along the guidewire, the guidewire can be restrained from being unintentionally pulled out from the duodenal papilla. Whereas, when the raised base of the endoscope in Patent Literature No. 2 is rotated toward the raised position, an intermediate portion of the guidewire is forcibly bent by the guidewire engaging groove that is formed through a side of the raising base. Accordingly, the intermediate portion of the guidewire is clasped between the guidewire engaging groove and the edge portion of the opening of the raising-base accommodation recess. Therefore, also with the case of the endoscope of Patent Literature No. 2, if an unintentional pulling force is applied on the guidewire, the guidewire can be restrained from being unintentionally pulled out from the duodenal papilla. Accordingly, in Patent Literature Nos. 1 and 2, it is relatively easy to externally pull out the catheter along the guidewire from the endoscope.
As described above, the operator, with the guidewire engaged with the wire-engaging groove (Patent Literature No. 1) or the guidewire-engaging groove (Patent Literature No. 2), pulls out the catheter protruding from the opening on the control-body side of the treatment-tool insertion conduit of the endoscope, along the guidewire, from the treatment-tool insertion conduit (and the patient's lumen). Subsequently, the distal end (internal space) of the flexible tubular treatment tool is inserted into the treatment-tool insertion conduit along the guidewire (that protrudes from the opening on the control-body side of the treatment-tool insertion conduit and is engaged with the wire-engaging groove (Patent Literature No. 1) or the guidewire-engaging groove (Patent Literature No. 2)), and the distal end of the treatment tool is inserted until reaching a desired location in the bile duct or the pancreatic duct, and a predetermined treatment is performed using the treatment tool. At this stage, since the guidewire is engaged with the wire-engaging groove (Patent Literature No. 1) or the guidewire-engaging groove (Patent Literature No. 2), when a force is exerted on the guidewire by the treatment tool, the distal end of the guidewire can be restrained from unintentionally being moved deeper than the desired location within the bile duct or the pancreatic duct.
Upon the treatment, using the treatment tool, ending, the treatment tool is pulled out from the treatment-tool insertion conduit (and the patient's lumen) of the endoscope along the guidewire. This pulling out of the treatment tool is carried out in the same order as the pulling out of the catheter.